"According to Reuters, a group of Facebook shareholders is looking to offload $1 billion worth of shares on the secondary market. Sources with direct knowledge of the situation say that the sale would value the company at more than $70 billion.

This would be one of the largest transactions of Facebook shares to date and it suggests that investors and employees are worried that Facebook’s growth cannot keep up with its market valuation. To some media theorists and critics, the ones that matter anyway, this comes as no surprise."

Other evidence: SharesPost, an online market for private shares, reported that Facebook stock hit $34 in January and is now down to $32. Facebook has declined to comment.